1. Field of the Invention
The present invention relates to a golf club and a golf club head, and specifically, to a metal golf club head of a large volume (at least 300 ml) and a golf club having such a head.
2. Description of the Background Art
A golf club head with a structure having a metal outer shell can be manufactured with a light and strong material, such as titanium or magnesium, for example. Various golf club heads of large volumes of at least 300 ml have been developed. On the other hand, since a larger golf club head tends to sacrifice control of the head, schemes for improving control of the head have also been developed.
One of the schemes for improving control of the head is a method of shifting the center of gravity of a golf club head toward the axis of a shaft. As one effect of shifting the center of gravity of the head toward the shaft axis, for example, a slice of the ball being hit will be reduced, i.e., the ball will be hit well. Additionally, control of the head in swinging may be facilitated.
Golf club heads in which the center of gravity is shifted toward the shaft axis as described above are disclosed in, for example, Japanese Patent Laying-Open No. 11-47318 and Japanese Patent Laying-Open No. 2002-35178.
In the golf club head disclosed in Japanese Patent Laying-Open No. 11-47318, a weight greater in a specific gravity than a head body is attached to the bottom of a hole for inserting a shaft such that the center of gravity of the head is shifted toward a heel portion side.
In the golf club head disclosed in Japanese Patent Laying-Open No. 2002-35178, a face portion of a head is reduced in thickness from a heel portion side toward a toe portion side such that the center of gravity of the head is shifted toward the heel portion side.
However, the golf club head of Japanese Patent Laying-Open No. 11-47318 requires to attach the weight inside the head, which complicates the manufacturing process of the head. Further, as the weight greater in a specific gravity than the head body is attached, the head increases in mass. This would hinder adjustment of the swing of the golf club, and therefore even when the center of gravity is shifted toward the heel portion side, control of the head can not fully be improved. Thus, there is a limitation in increasing the volume of the head.
As to the golf club head of Japanese Patent Laying-Open No. 2002-35178, the face portion can not be greatly reduced in thickness for durability problems. Thus, the effect related to the reduced weight of the toe portion is limited.